Affordable assistive listening device for the hearing impaired / hard of hearing at church

For less than $100 we set up a small FM transmitter (radio station) to help people hear and understand what is said in church.

Why a hearing aid may not be sufficient for hearing in church
Mother's hearing had deteriorated to the point that she was not understanding anything at our church, First Assembly of God in Benton, Arkansas. Now that she can hear and understand most of what is said, she enjoys attending church again. Mom simply puts an FM radio in a pocket and puts an ear bud in one ear (the one without the hearing aid). The church purchased several small FM radios with ear buds so that others with hearing difficulties can also benefit.

To a person with normal hearing it is not obvious why some people have difficulty understanding what is being said. The PA system makes it loud enough for everyone to hear unless they are nearly deaf. The people who cannot understand in church may be able to hear thunder even in the distance, may be able to hear a car door close outside, and may be able to hear other low to medium frequency sounds. Perhaps they can even hear some limited high frequency sounds. However, they may have trouble hearing certain higher frequencies well enough to understand speech. Loss of high frequency hearing, echoes, or change in brain function (auditory processing) can contribute to the inablity to understand speech in an auditorium.

A solution that works well for Mother (and other hearing impaired people) is to pipe the sound from the preacher's microphone directly to their ear buds or headphones. A low power transmitter sends the signal out from the PA system, and a small FM radio picks it up. There is no limit to how many receivers can pick up the signal (as long as they are close enough to the transmitter). We have found that digital FM radios must be used. I have tried a knob tuning (analog) radio which works fine as long as it is very close to the transmitter. The trouble is that when the receiver is separated from the transmitter by just a few feet, the receiver would tune in a stronger station. This was not a problem with the digital tuning radio. The FM radios are powered by batteries. We use rechargeable NiMh batteries which seem to work fine. The initial cost is high for rechargeable batteries, but since they can be recharged more than 500 times, the cost over time is low.

Setting up the system is fairly easy. Almost every church has a sound system that a transmitter can be hooked to. We split the cassette tape input to feed the transmitter (one line from the sound system feeds both the cassette tape recorder and the transmitter). The transmitter is from C. Crane. It has a small telescopic antenna which gives it more range than cheaper transmitters that have no external antenna. We found an unused FM channel, set the transmitter and radios to that channel, and we had an operating assistive listening system.

We have found that the reception is somewhat noisy in several parts of the auditorium due to the extremely low transmit power. We have learned where we have to sit to get reception, and we can sometimes move the FM radio a few inches to find reception clear enough to be understandable. The FCC only allows very low power unlicensed transmitters in the FM broadcast band (where FM radio stations broadcast). It would be nice to have noise-free reception in the entire auditorium, but what the FCC allows is better than nothing. There are more expensive systems that operate in other frequency bands and have more range, but special receivers must be used with those systems.

Even people with hearing aids can benefit from this system, because it cuts out the echoes and noise. People with hearing aids in both ears would need to use headphones, or take one hearing aid out to make room for an ear bud. Open-air headphones do not work very well with hearing aids. Closed headphones are much better since they keep out much of the echo and noise. Noise cancelling headphones should work even better, although they are larger and more expensive. If your hearing aid has a T-coil, then you would think that headphones would work like a telephone and allow you to hear the headphones without hearing all the echoes and noise from the mic in the hearing aid. The headphones we tried with the hearing aid T-coil just did not work. Your mileage may vary. Another option for a T-coil hearing aid is a neck loop, but we have not tried that.

Mother has encountered some problems with the music during church, but these problems can be fixed with the help of the sound person.

  1. The music is much louder than the sermon. If the sound man does not turn down the volume to the transmitter, the music is very distorted. The audience can tolerate some loud music, but transmitters and tape recorders need to be fed the same volume all the time. If it is too loud, it will be distorted. If it is too low, then the listeners will not be able to turn the volume up enough to hear anything.

  2. Hard of hearing people generally have trouble understanding the words of songs if the vocals are about the same volume as the instruments. To solve this trouble the sound person needs to do a special mix for the hearing impaired which would have the instrumental music at a very low volume.

I have an untried idea of how to cope with problem 1 -- levels (volume) that fluctuate wildly between music and speaking. Run the audio through a VCR to take advantage of the AGC (Automatic Gain Control) circuit. VCRs can handle pretty loud audio without distortion. The only trouble is that loud audio results in heavily compressed output which can be tiring to listen to (causes listener fatigue). If the VCR is High Fi, it would be a good way to archive the entire service with no breaks for turning the tape over (or reversing) as happens with cassette tape.

Of course a transmitter with a built in AGC would also help solve the problem of wildly differing volumes. Some more expensive systems include this feature.

Hearing loss is becoming more and more common. If you think you or other hearing impaired people in your church could benefit from an assistive listening device, using FM radios is a cheap way to get started. You can always graduate to a better system later.


Hearing Loss Web: An encyclopedia of information about hearing loss
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C. Crane

Ramsey Electronics

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